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#include <iostream>
#include <vector>
#include <stdio.h>
#include <queue>
#include <set>
#include <string>

using namespace std;

const int INF = 1000000000;
int mn;
int n, m;
vector<set<int>> g;
vector<pair<int, int>> edges;

void bfs(int s, vector<int> &d){
    d[s] = 0;
    vector<bool> used(n);
    used[s] = true;
    queue<int> q;
    q.push(s);
    while(!q.empty()){
        int u = q.front();
        q.pop();
        for(auto i = g[u].begin(); i != g[u].end(); i++){
            if(!used[*i]){
                q.push(*i);
                used[*i] = true;
                d[*i] = d[u] + 1;
            }
        }
    }
}

vector<vector<pair<int, int>>> ng;
vector<bool> used;
vector<int> tin, fup;
int timer;
vector<pair<pair<int, int>,int>> ans;

void dfs(int v, int p = -1) {
    used[v] = true;
    tin[v] = fup[v] = timer++;
    for (size_t i=0; i<ng[v].size(); ++i) {
        int to = ng[v][i].first;
        if (to == p)  continue;
        if (used[to]){
            fup[v] = min (fup[v], tin[to]);
            if (fup[to] > tin[v])
                ans.push_back(make_pair(make_pair(min(v, to), max(v, to)), ng[v][i].second));
        }
        else {
            dfs (to, v);
            fup[v] = min (fup[v], fup[to]);
            if (fup[to] > tin[v])
                ans.push_back(make_pair(make_pair(min(v, to), max(v, to)), ng[v][i].second)); //what have i written here?!
        }
    }
}

void find_bridges() {
    timer = 0;
    for (int i=0; i<n; ++i)
        used[i] = false;
    for (int i=0; i<n; ++i)
        if (!used[i])
            dfs (i);
}

int main()
{
#ifdef _DEBUG
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    scanf("%d%d", &n, &m);
    g = vector<set<int>> (n);
    edges = vector<pair<int, int>> (m);
    for(int i = 0; i < m; i++){
        int cur1, cur2;
        scanf("%d%d", &cur1, &cur2);
        cur1--; cur2--;
        g[cur1].insert(cur2);
        g[cur2].insert(cur1);
        edges[i] = make_pair(cur1, cur2);
    }
    vector<int> d1(n, INF), d2(n, INF);
    bfs(0, d1);
    bfs(n-1, d2);
    mn = d1[n-1];
    //vector<pair<int, int>> br; //draft "bridges"
    //d1[u] + 1 + d2[v] == mincost  d1[v] + 1 + d2[u] == mincost
    ng = vector<vector<pair<int, int>>> (n);
    tin = fup = vector<int> (n);
    used = vector<bool> (n);
    for(int i = 0; i < m; i++){
        int u = edges[i].first;
        int v = edges[i].second;
        if(u != v && (d1[u] + 1 + d2[v] == mn || d1[v] + 1 + d2[u] == mn)){
            //br.push_back(edges[i]);
            ng[u].push_back(make_pair(v, i));
            ng[v].push_back(make_pair(u, i));
        }
    }
    dfs(0);
    sort(ans.begin(), ans.end());
    set<int> s;
    //if(ans.size() < 2 || ans.size() > 1 && ans[0].first.first != ans[1].first.first && ans[0].first.second != ans[1].first.second)
    //  s.insert(ans[0].second);
    for(int i = 0; i < ans.size(); i++){
        bool flag = false;
        while(i < ans.size()-1 && (ans[i].first.first == ans[i+1].first.first && ans[i].first.second == ans[i+1].first.second)){
            flag = true;
            ++i;
        }
        if(flag)
            ++i;
        if(i < ans.size()){
            s.insert(ans[i].second);
        }
        //cout << ans[i].first.first + 1 << " " << ans[i].first.second + 1 << " " << ans[i].second + 1 << endl;
    }
    cout << s.size() << endl;
    for(auto it = s.begin(); it != s.end(); it++)
        cout << *it + 1 << " ";
    //cout << ans.size() << endl;
    return 0;
}